Fuel Sending Unit Installation on a 1965 Corvette
 

Just finished replacing the fuel sending unit on my 1965 coupe and thought it might be beneficial to share a few photos and go over the procedure for anyone thinking about undertaking the same. My old unit was bad as it has an open in the resistance wire that the two terminals on the unit connect. It measured an infinite resistance between the tan wire and the black/w/pink wire terminals at the unit. Here’s a pic of the old unit still in place, but with the fuel tank drained and with the hose connecting the sending unit and the fuel line removed. My spare tire carrier was already out of the car and stored, I haven't carried a spare tire in years. Needless to say, you'll need to remove the spare tire and carrier in order to properly access the sending unit.

http://i32.photobucket.com/albums/d1...t/IMG_1725.jpg

I drained the tank (it was completely full, wouldn’t you know!!) by clamping the rubber fuel connector line at the sending unit, cutting it in the middle, and catching the fuel as it drained from the tank in a suitable container. Once drained I then jacked up slightly the right rear of the car to move any remaining fuel away from the sending unit. I then removed the locking ring with a “make do” tool that would span two opposite flanges on the retaining ring. I know they make a tool for this, but I’ve never owned one and have never had a problem using a method similar to that shown in the photo below for removing or installing the sending unit. If you choose to do the same, exercise care that you don’t put any pressure on the electrical connectors, I’m sure they could be easily broken. Here’s how I managed this time, just happened upon this in a tool drawer and thought it looked about right for the task at hand. And, it was . . . . .

http://i32.photobucket.com/albums/d1...t/IMG_1730.jpg

Once the retaining ring has been removed, it’s a simple matter to work the old sending unit out of the tank. I think I had to flex the filter just a bit to get the old unit out. Other than that, no problem. Here’s a couple of photos coming out.

http://i32.photobucket.com/albums/d1...t/IMG_1736.jpg

http://i32.photobucket.com/albums/d1...t/IMG_1737.jpg

The old unit was an original and had been in place since 1965. The flat metal connector was covered by an insulating tube and is clearly visible in the upper photo. By now it was so brittle that it cracked under only light finger pressure as is shown in the lower photo.

http://i32.photobucket.com/albums/d1...t/IMG_1738.jpg

The new unit is the one by Fargo Automotive which JohnZ reviewed some time back and thought it should be a suitable replacement. It has threaded nuts securing the terminals in place, which should be more secure than some of the other aftermarket units using the “press on” retainers for the terminals. I checked the resistance on mine, however, and found it to be 120 ohms rather than the 90 ohms that I think was specified for the original. It shouldn’t matter too much, however, but it might make the unit a little more inaccurate at full tank readings. It should however be more accurate as the tank empties I’d think. Here are a few pics of the unit . . . . . .

http://i32.photobucket.com/albums/d1...t/IMG_1731.jpg

http://i32.photobucket.com/albums/d1...t/IMG_1732.jpg

http://i32.photobucket.com/albums/d1...endingUnit.jpg

http://i32.photobucket.com/albums/d1...endingUnit.jpg

http://i32.photobucket.com/albums/d1...t/IMG_1735.jpg

You’ll notice the last shot shows the flat band connector on the new unit, the same type of connector as was used on the original. However, I included this shot to show how I had slightly “rotated” the band at each of the terminal ends to move the band away from the fuel tube. I did this because of the recent post by a forum member showing how his unit had failed when the band’s insulation wore through because of rubbing contact with the fuel tube. The slight realignment should cure this problem.

The photo below shows the only “hitch” I ran into when installing the new unit. It may be a little difficult to see, but the needle nosed pliers were used to bend the metal tab on the new sending unit such that it was a little closer to the sending unit housing. The metal tab shown is the upper stop for the fuel float, and as shipped it “stuck out” a little further from the sending unit than is shown in the photo. A little adjustment with the needle nosed pliers put it into the position shown, allowing easy insertion through the hole in the fuel tank. It was originally “just far enough” out to cause it not to go through the hole. Small problem, easy fix!! Also note the greased “O” ring seal in place, awaiting installation.

http://i32.photobucket.com/albums/d1...t/IMG_1739.jpg

Finally, with the new unit in place, the retaining ring and new fuel hose connected, I lowered the car from the lift and added 3-4 gallons of fuel to check for leaks before connecting the electrical wiring. Fortunately, no leaks, no drips, no errors!! Here's a picture of the new unit in place and buttoned up to check for leaks before I connected the electrical wires.

http://i32.photobucket.com/albums/d1...t/IMG_1741.jpg

By the way, I picked my Fargo sending unit up from the Car Shop in Orange, California thanks to a tip from another Corvette Forum member. The price was what really surprised me, just about half of what various other vendors are quoting these days! Also got a catalog from these folks with a lot of Corvette parts, looks interesting.

I hope this proves useful to any of you guys undertaking a similar replacement, let me know if I can answer any questions or be of any assistance.

Original Fuel Sending Unit Restoration
 

Thought I'd add a little update to this thread for information. I just checked with John Wolf in Ohio about rebuilding an original C2 fuel sending unit and was quoted $135 plus return shipping for a functional rebuild of my gage. This would typically include a new float, fuel strainer sock, and replacement of the resistance coil (mine is open).

Should you want the unit tin plated as the original was, add $30 to the $135 for a total of $165.

Sounds reasonable, I'll probably have mine rebuilt functionally as I don't ever plan on owning a show car.

:thumbs:

Ron, this is an outstanding post and should help many forum members in the future. Great job!

That's an error rate of over 30%:ack:. I had my original one restored by John Wolf. Looks AND functions like new.:cheers:

Jim

Great write up Ron, thanks for taking the time to include the pictures!

Don

Well done Ron!

For those of you about to tackle this for the first time ---
don't overlook the tip about jacking up the car. (Unless you want 91 octane armpits).

My experience has been north of 50%. I will file John Wolf's number in my contact list.

True enough. Not sure if they're all that way or not these days. From what I remember in JohnZ's article, the Fargo unit he checked measured just at 90 ohms, same as the original Corvette. And, if I remember correctly all (or almost all) of the GM fuel sending units are also 90 ohm units. I'm thinking I may check around and find a good GM unit & see if the resistance coil pack can be easily swapped into the Corvette unit.

For what it's worth, over 20 years ago I repaired the original Corvette unit that I just pulled out. The resistance wire was open, broken right at the end as I recall, so I unwound one wrap so it would reach the terminal and reconnected it to the terminal. Worked fine for many years, although it was off just slightly at the "Full" mark on the gage inside due to having just slightly less than 90 ohms resistance. But, it served my purposes. I may check it out again myself this time . . . .

Also for what it's worth, the Fargo unit should only measure incorrectly at the full side of the tank, and gradually become more accurate as it reaches the empty marking. The Fargo unit got me back on the road and running for about 25% of the price of a restoration and I can always have the original restored. For my purposes I think that'll be good enough, I'm more concerned about running out of gas than I am knowing to the quart how much is in the tank. And, when it gets near empty I always fill it to the top anyhow.

Thanks for the kind comments on the writeup and the pictures, I was hoping the information might prove useful to some of the forum members in the future. I've also corrected the broken links to two of the closeup photos of the Fargo unit. Those two were actually furnished to me by the vendor I mentioned earlier in order that I could make a decision on the purchase. The vendor's folks were actually quite helpful, willing to go the extra mile. Speaks volumes!!

:thumbs:

Ron,thanks for posting this. :thumbs:

I followed the thread and replaced my 64 sender today with no real hitches. The tip about jacking the pass side of the car was great...its one of those things that if you just stand back and think about it, it should be obvious...but to guys like me it may not always be THAT obvious until AFTER you get a face full of gas.

A couple of add on notes for anyone else like me who never did this before:

- The original was still in the car & replaced it with the Paragon sender #3794. Ohmed out fine, fit very well but had to bend the long tube just a hair so everything could wiggle around and finally go in.

- Fortunately, I also ordered the new steel lock ring and a spare O ring (just in case) . Didnt need the O ring; but the orig lock ring didnt exert enough enough oomph to seal the aftermarket sender 100%, so a little weeping. Jacked it back up, changed the lock ring, and no weeps or leaks.

- I was trying to figure out the S & I wires as the new one had the posts opposite OEM. BUT the blinding obvious struck me here...there is a 'fat' post & a skinny post for the respective wire to plug onto, so duh, no issue there.

Best part was when I re-hooked the batt and put the key on...I had a working gas gauge. Reached inside with a painters stick and moved the float up and the needle moved accordingly. Sweet, no more driving around with a gal can of gas or always looking inside the tank with the flashlight before and during drives.

Thanks Ron & all the guys who contributed to making this a way helpful thread,

George
:cheers:

-

Good info - Thanks!

Thanks for the kind comments, George, and thanks also for the items you've included as well. Good to know about your experience with the Paragon unit, sounds like they must have a different supplier.

I personally think this thread would be a good candidate for a sticky at the top, a lot of other good information in the thread other than my own!

Ron

Fuel gage sending unit O ring
 

This post is a big help for me, I'm going to change my sending unit on my '63. Its been 40 years since I did any "work" on a car and now that I'm retired I need something to do. Any way, I like to cover all bases and know as much as possible about a job before I start. After reading the article I have only one question, The O ring has a tab on it ( and it might be obvious once I take the old unit out) but which way does it go? On my new unit there are two indentations,one at each terminal. It makes sense to me that the O ring tab would fit into the indentations but there is only one tab and two indentations.

Rick,
Thanks much for the comments, glad that this thread is able to help so many of the forum guys who've also helped me in the past!!

As far as the tab on the "O" ring, it's been some time since I replaced mine (I've done the job before, but even longer back!) and I don't remember where the tab was oriented. I think you'll be OK with the tab in any position around the sending unit as long as the "O" ring is seated without interference on the outer rim of the sender. I think the ring is thick enough that the tab doesn't enter into the picture as far a sealing the sending unit into the tank.

You might try checking your old "O" ring when you remove the sending unit and see if you can tell where the tab was installed on it, my suggestion.

Ron :thumbs:

Thanks Ron, I just sat down after putting the sending unit in. On the first attempt it leaked (as with my luck, it would) but all I had to do was jack up the passenger side of the car to stop it. I tried again, repositioned the O ring and it worked perfectly. Apparently the tab is there for looks or maybe to confuse someone like me.
Once again thanks for the help.

The Car Shop and the Truck Shop have some good deals. I found them a few years ago at the Charlotte Autofair. The only negative is that they don't really like to return any products...

Hitch

Another successful install, congratulations Rick. Glad it went well!!

Ron :thumbs:

I am getting ready to replace the fule sending unit on my 67 Vette. I was wanting the clean out the tank to remove some slight rust, etc on the bottom. Anybody have any suggestions about what to use to clean it with and should I try and add a sealant after cleaning. I was thinking of using a 10% acid solution.

If it has rust in it, replace it - they're cheap; any acid cleaners and snake-oil "sealers" will come back to bite you, especially with E10 fuel. :thumbs:

Great thread Ron :thumbs:

What kind of grease did you use on the O ring?

FYI, as of the first part of this year, the truck and car shop in Orange ca. no longer sells corvette parts. That's a shame. Ive been buying parts for my Impala there for over ten years.